Internal combustion engines of an automobile may utilize an engine control unit (ECU) for electronically controlling engine operation. For example, the ECU may control the engine ignition system the engine as well as other vehicle or engine components, and may also be coupled to a plurality of sensors. In one example, the ECU may be located near or in the engine compartment such that significant heat energy generated by the engine and related components may be transferred to the ECU. As such, it is possible that there may an undesirable temperature rise due to heat buildup in the ECU, which may in turn cause degradation of the ECU and thus engine or other vehicle operation. Further, this heat buildup may be exacerbated by conduction or other transfer of heat from the systems adjacent to an enclosed space in which the ECU is located, and by the heat generated from the ECU itself.
To control or reduce ECU temperature, various forms of heat management may be used. One approach aims at cooling the ECU, either passively or actively. Another approach aims at reducing the amount of heat generated by the ECU. In one example approach aimed at cooling the ECU when a risk of overheating is imminent, heat in the ECU may be dissipated by switching on a fan, increasing the rate of coolant flow, or altering the temperature of the thermostat coupled to the engine cooling system. In cooling the ECU, airflow by air current through the enclosure or by a fan may be used to maintain the desired operating temperature of the ECU. Such an approach is described in U.S. Pat. No. 6,655,326.
However, the inventors herein have recognized that in certain operating systems, for example, when the climate control system is turned off or a recirculation mode is selected, airflow around the ECU and/or through its enclosure may be reduced or stagnated. As such, this may result in insufficient cooling of the ECU and potentially increasing a possibility of heat related degradation of the ECU. For example, when the climate control system is turned off, fans coupled to the system may not operate and reduced or no airflow may be blown past the ECU and/or into the passenger compartment. Likewise, when the recirculation mode is selected, either automatically or by a customer selection, there may be reduced or no airflow from exterior to the passenger compartment past the ECU because the vents are closed. Therefore, there may be insufficient cooling of the ECU under these and other situations.
The above issues may be at least partially addressed by compelling ventilation of the ECU enclosure during selected operating conditions in which ECU temperature may be higher than desired and overriding customer settings. For example, during selected higher ECU temperature conditions, the system may temporarily enable a climate control blower fan even when a customer has set the fan to off. Alternatively, the system may temporarily increase fan speed above that set by the operator. Likewise, the system may temporarily disable a recirculation mode (e.g., by opening or adjusting various communication vents) even when a customer has set the mode to recirculation.
Further still, in the example of an automatic climate control system, where the system sets various conditions such as fan speed and/or recirculation mode in response to a customer temperature command, these settings may be temporarily overridden to increase ECU cooling. Note that the conditions of ECU over-temperature may include operation at a high engine speeds (which may produce more heat in the ECU), operation at high load, (which may produce engine system heat that may be transferred to the ECU enclosure), operation at high ambient temperature (e.g., greater than 80 degrees F., for example), and/or operation at high measured temperatures in or near the ECU.
In this way, it is possible to increase the heat transfer from the ECU during selected ECU over-temperature conditions, for example.